Hello sean, welcome to the forums.
To start off, I'd recommend this website I found while doing research on a new laptop I recently purchased.
http://www.notebookcheck.net/
Now, in terms of boutique vendors, there is indeed a myriad of them out there, but the best choice is to look how long they've been in business, what kind of reviews they got from gaming community and also from official agencies like BBB (
http://www.bbb.org/)
Basically, when looking at a custom vendor look for the link to their BBB rating, that will be able to give you some objective information about the business.
Another very big issue to consider is location. Many of these custom vendors offer wonderful lifetime support and 3 year warranties. The problem is, you want them to be relatively close to you, if you ever need to mail the laptop in for service. Because for example, you live on east coast, and you buy from digital storm, who are in California; if you need to mail laptop in for service it takes about a week to get to CA from east coast, they will need some time to work on it, say a week and then ship it back for another week. In total you sitting without your laptop for 3 weeks to month. While if you find a local or relatively close vendor, shipping to them will take about a day or two, that's a lot better.
Now, to recommend some vendors by location I found in my own research recently:
West coast:
http://www.digitalstormonline.com/ - CA
http://www.falcon-nw.com/ - WA
Mid west:
http://www.xoticpc.com/ - NE
East Coast:
http://originpc.com/ (former alienware executives) - FL
http://www.maingear.com/ - NJ
Now, out of those, the cheapest one I've found to be are xoticpc and digital storm (these are mostly the preffered ones by the TH community). DS has a little less customization options, but they have nice premade models to select from, you are sure to find something that will suit you, xoticpc just has nice prices and good options. origin is former folks from alienware that created their own company after alienware got bought out by dell, they haven't been around for very long, but I haven't seen any major complaints about them. falcon nw, has been around for quite a while, but they are pricey, so is maingear.
That's as far objective as I'll go, rest of choosing is up to you.
From personal experience, I've got very similar needs to yours myself and here's the laptop I just bought myself:
http://www.xoticpc.com/sager-np8150-clevo-p150hm-p-2972...
for me a major factor was the casing layout, I knew I wanted a clevo case after looking around at all different ones on the market. your priorities might be different, but, this will give you a place to start.
All best, and hope this helps you to make the choice you'll be happy about